Trimming mechanism for sewing machines



Sept 20, 1938- H. J. GALLANT E1- AL 2,130,340

TRIMMING MECHANISM FOR SEWIN-GvMACHINES Filed 0G12. 50, 1937 2 Sheets-Sheet l uw 3. a J j la,

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TRIMMING MECHANISM FOR SEWING MACHINES Filed Oct. 30, 1957 2 Sheets-Sheet 2 Patented Sept. 20, 1938 AUnirse stares TRIMMNG MECHANISM FOR SEWING MACHINES Hubert J. Gallant, Exeter, N. H., and Ernest A. Gauthier, Amesbury, Mass.

Application October 30, 1937, Serial No. 171,934

7 Claims.

This invention relates to improvements in trimming mechanism for sewing machines.

More especially it provides an improved trimming mechanism for coaction with the stitching and work-feeding mechanism of a Singer sewing machine of walking foot type, having a flat bed as distinguished from a cylindrical bed.

Mechanisms for trimming as the stitching progresses have heretofore been available for use only on sewing machines not having a walking foot feed, or on walking foot machines having a cylindrical bed; and have been complicated and cumbersome devices. No one, so far as we are aware, has successfully combined a trimming mechanism, in a simple and unobtrusive practicable form, with the regular stitching and workfeeding mechanism of a walking foot iiat bed type of sewing machine.

The invention has among its objects to provide a trimmer mechanism which is simple, as compared with devices now available, and, for mounting and guiding the trimmer blade, to utilize for the most part present standard sewing machine elements.

Another object is to provide simple yet effective connections for actuation of the trimmer blade in timed relation to the sewing and workfeeding functions of the machine.

A further object is to provide means for the op erator to throw the trimmer mechanism into and out of action, at will, without affecting the regular functions of the machine.

It is another feature that the bed plate for use with the trimmer can be made as a modification of one which is already available as a standard type.

For holding the trimmer blade, the inventio provides a plate guided slidably on the presser bar of the machine, below the machine head. A second guide element may be fixed in the under face of the head, for combining with the presser bar to maintain the plate in a horizontal plane, and to -hold it against turning. A latch link is adapted to engage the plate operatively when the plate is pressed downward, so that the plate 'and its blade are reciprocated by the latch link which.

is itself reciprocated by a link of the regular walking foot actuating mechanism. A disengaging of the latch lets a spring move the trimmer to its uppermost position where it is inoperative.

A bed plate of the sort used with trimmers on machines not of the walking foot type may be modified to suit our present requirements, by converting the rectangular feed slot to an inverted L-shaped slot, and by providing a bracket on the under side of the plate, to support the incidental cut end of the shearing bar of the plate.

It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty exist in the invention disclosed.

In the acompanying drawings:

Figure 1 is an end elevation of a sewing machine head, embodying features of the invention;

Figure 2 is an elevation looking from the leftv in Figure 1 at the rear side of the head;

Figure 3 is an elevation of the lower portion of the head, looking from the right in Figure 1 at the front side of the head;

Figure 4 is an elevation of the lower portion of e the head, looking from the left in Figure 2;

Figure 5 is a plan, in section on 5 5 of Figure l;

Figure 6 is a plan of the bed plate; and

Figure '7 is a view like Figure l of the lower portion of the head, but with the trimmer plate and blade in elevated inoperative positions.

Referring to the drawings, the invention is portrayed as embodied in a walking foot type of Singer sewing machine, which has an usual head Iii, needle bar I2 and presser bar I4. The needle bar and presser bar are mounted side by side in the head, for vertical reciprocation in timed re lation by usual mechanism (not shown) Within the head. The needle I6 is carried at the lower end of the needle bar; and the presser foot it is carried at the lower end of the presser bar, for co-acting with the corrugated feed dog 20 which works in the slot 86 in the flat bed plate 22 of the machine.

A walking foot 24 is mounted on the lower end of a bar 26 which hangs by gravity from its pivotal mount at 28 on an L-shaped lever 3i). A leaf spring 32 urges this bar forward so that its foot 2d engages the presser foot I8, at the times when the Walking foot is elevated with respect to the work.

The Walking foot 24 and its suspension bar 2G are actuated in vertical directions by a crank arm 34 on rock shaft 3B. Mechanism (not shown) within head Ill, reaching out at the back of the head, rocks shaft 36 in timed relation to the movements of the needle bar and presser bar. A link 33 connects crank arm 34 to one arm of the L- shaped lever 36, whose other arm is connected to a block lil which is secured to and carried by they presser bar I4, and which is slidable vertically on the fixed guide 42.

The foregoing is descriptive of mechanism which is old and well known. In operation, the

presser foot engages and holds the work between.

itself and the feed dog 20 while the needle pierces the Work. As the needle is being elevated, the walking foot 24 is moved downward into engagement with the work, and the presser foot I8 is elevated a little to disengage itself from the work. Then the feed dog 20 moves rearward, and the work is carried with it, pinched between the feed dog and the walking foot which moves rearward against its leaf spring 32. As the needle starts downward, the presser foot I8 again engages the Work, the walking foot 24 is lifted, and spring 32 swings it back to its forward position.

According to the invention, a horizontal plate 44 for carrying the trimmer blade 50 is mounted below head i8 and can be adjusted vertically between a depressed position as represented in Figures 1-4, where it is operative through a range of vertical travel, and an elevated position, as seen in Figure 7, where it is inoperative. A convenient arrangement is to mount plate 44 slidably on the presser bar I4, and on a short, xed post 45 which is secured in the head to project downward parallel to the presser bar. A coil spring 48 tends to draw plate 44 to its upper inoperative position of Figure 7. A

A trimmer blade 50 is secured on plate 44, adjustably as` by the screws 52, the particular blade shown being of a well known variety heretofore used on other types of sewing machines. In the upper position of plate 44, the blade 50 is elevated well above the level of the work on bed plate 22.

The invention coordinates the operations of the walking foot and trimmer so that the trimmer blade, when depressed and connected for operation, makes a downward cutting stroke each time the walking foot is lifted from the work at the end of each feed advance of the work. To this end, a bell crank is pivoted at 54 on a Xed part of the head I8. One arm 56 of the bell crank is secured to the link 38 at a mid-location 68, and the other arm 52 of the bell crank is connected at 64 to a latch-link 66 whose lower end eX- tends within a slot 68 (Figure 5) in plate 44. A notch 'I8 near the lower end of the latch-link is adapted to engage the rounded edge wall 'l2 of slot 58, thereby to connect the plate operatively with the latch-link. A leaf spring 14 continually urges latch-link G5 against said edge 12 so that, when the plate 44 is moved downward, as by a person pressing down on nger piece 16, the latch-link snaps into plate engagement. The plate and the trimmer blade 50 which it carries are then reciprocated vertically by movements of link 38.

The trimmer thus can function in timed relation to the stitching and feeding of the work. And, quite as important, the trimmer may be thrown outl of service by means of handle '|8, by merely disengaging latch-link 66.

Figure 6 shows in plan an improved bed plate 22 devised especially for coacting with the described trimmer attachment. It is provided with a slot 88 which, as viewed from the front, is in the shape of an inverted L, within the breadth of whose longer limb the feed dog 28, the presser foot I8 and the walking foot 24 may coact for the holding and-for the feed, with the walking foot extending laterally into the space occupied by the broad sharter limb of the L. A trimmer plate of a shape used on another type of sewing machine, having a straight slot, may be modied to suit the requirements, by removing a portion of the adjacent metal strip 86 which is present in that type, and by providing a bracket 82 on the under face of the bed plate, with finger 84 for supporting the cut end, at what was the middle, of this metal strip 86. A usual springpressed block 88 yields, as the blade is forced down through the crack at 90, and meanwhile yieldingly presses the trimmer blade against the strip 86, for shearing action. The needle passes down through hole 92 in strip 86.

The invention involves few parts and may be embodied in standard sewing machines of well known types without disturbing present mechanism.

In Figure 6 the bed plate 22 is shown as it would appear in plan when standing at the back side of the machine, i. e., the slot has the described inverted L shape when viewed from the front side of the machine.

We claim as our invention:

1. In a sewing machine having a work support and stitch forming mechanism, with workfeeding mechanism and a head overhanging, including a presser bar with presser foot, a walking foot, and actuating means therefor; the combination therewith of a trimmer blade having mounting means slidable on the presser bar below the said head; means for connecting said blade to said actuating means at the will of the operator, for reciprocating the trimmer blade in timed relation to the action of said work-feeding mechanism.

2. In a sewing machine having a work support and stitch forming mechanism, with work-feeding mechanism and a head overhanging, including a presser bar with presser foot, a walking foot, and actuating means therefor; the combination therewith of a plate mounted slidably on the presser bar, below the said head; a trimmer blade xed on said plate; means for connecting said plate to said actuating means at the will of the operator, for reciprocating the trimmer blade in timed relation to the action of said work-feeding mechanism.

3. A sewing machine as in claim l, wherein the said connecting means is a lever pivoted on said head and having one arm connected to said actuating means; and means at the other arm of said lever for operative connection to the slidable means.

4. A sewing machine as in claim 2 wherein the said plate is ,yieldingly held by a spring in an elevated inoperative position, and wherein said connecting means is a lever pivoted on said head and having one arm connected to said actuating means, and its other arm carrying a latch-link suspended and spring-pressed into sliding engagement with an edge of said plate; said latchlink having a notch therein adapted to move into latching engagement with the plate when said plate is depressed to latch-engaging level.

5. A sewing machine as claim 1 wherein said mounting means for the trimmer blade is additionally guided by a guide post projecting downward from said head in parallelism with said presser bar.

6. A sewing machine having a head, a presser bar with presser-foot mounted for reciprocation in the head, a trimmer blade, a guide post projecting from said head, at a distance from said presser bar and parallel thereto, a carrier for said blade mounted slidably on said presser bar and said post, and means, actuated in timed relation to said presser bar, adapted for'actuating connection to said blade carrier, whereby the said blade carrier moves in timed relation to the presser bar.

7. A sewing machine as in claim 1 wherein the machine has a flat bed with a at bed plate which has an inverted L-shaped slot for accommodating the feed dog and Walking foot, and has a bar set along the vertical limb of the L, having a hole for passage of the needle, said bar constituting one blade of a shear, and ending within the inner angle of said L, and wherein the under side of said bed plate has a bracket sustaining the end of the shear bar, and the upper side 10 of said bed has, in the plane of the shear bar, a

block yieldingly urged laterally against said shear bar, said block having a groove in its edge for reception of the leading end of said trimmer blade between said block and said bar, with said block yielding away from the shear bar as the blade moves downward, whereby said block presses said blade into shearing relation with said shear bar.

HUBERT J. GALLANT.

ERNEST A. GAUTHIER. 

